var util={
    /*
    * element:目标元素
    * type:绑定的事件类型
    * handler:事件处理程序
    * */
    addHandler:function (element, type, handler,isBubbling) {
        if (element.addEventListener) {//DOM2支持
            element.addEventListener(type, handler, isBubbling || false);
        } else if (element.attachEvent) {//IE兼容
            element.attachEvent("on" + type, handler);
        } else {//DOM0
            element["on" + type] = handler;
        }
    },
    removeHandler: function (element, type, handler,isBubbling) {
        if(element.removeEventListener){//DOM2支持
            element.removeEventListener(type,handler,isBubbling || false);
        }else if(element.detachEvent) {//IE兼容
            element.detachEvent("on"+type,handler);
        }else {//DOM0
            element["on" + type] = null;
        }
        }
}